| Guanidine gum fracturing fluid is the main type of fracturing fluid used in the process of fracturing.Because the composition of gum gum fracturing fluid is complex and the treatment is difficult,the current treatment method of gum gum fracturing fluid is oxidation-flocculation method.However,the chemical composition of the treated fluid is still complex.Direct discharge back will pollute the environment and cause a great waste of water resources.Therefore,the determination of gum gum reflux fluid is carried out.Whether the content of each component satisfies the requirement of fracturing flowback and eliminating the disadvantageous factors of boron and metal ions in flowback fluid for the reuse of fracturing fluid is of great significance.In this paper,the physical and chemical properties of the backflow fluid are quantitatively analyzed by means of large-scale instruments and chemical methods,combined with the influence of metal ions on the performance of fracturing fluid,whether the backflow fluid can meet the requirements of direct reallocation or not is analyzed'The effect of Boron on the viscosity of the base fluid is eliminated by screening the type and amount of boron complexing agent,and then the crosslinking agent,gel breaker and inhibitor are determined.With the addition of fungicides and other medicines,the properties of the reconstituted fracturing fluid can meet the requirements of fracturing construction.According to the dosage of the analogue backflow fluid,the treatment and reuse technology of the on-site backflow fluid is determined.In addition,the complexing ratio of boric acid or borax and complexing agent and the analysis of complexing products are studied.The reuse of the clean fracturing backflow fluid is achieved by adding different amounts of medicines into the original formula.Finally,the properties of guanidine gum fracturing fluid prepared directly from clean fracturing fluid were studied.The experimental results show that the concentration of anions,cations and insoluble substances in the backflow fluid are determined by the existing methods,and the method of determining the content of soluble guanidine gum in the backflow fluid is established.In addition,the influence of different metal ions on the viscosity of fracturing fluid is studied,and the upper limit of metal ion concentration satisfying the performance of fracturing fluid is determined.The experimental results show that the following ions concentration in fracturing fluid exceeds a certain value and the viscosity decreases to less than 50 mPa s at 70 ?.Ca2+.concentration is 2000 8g/L,Mg2+ concentration is 2000 mg/L,Fe3+,concentration is 20/g,L.The formulation of simulated backflow fluid was determined by fracturing fluid viscosity,temperature resistance and gel breaking inhibition.The concentration of thickener was 0.3%,the concentration of borax crosslinking agent was 0.5%,the cross-linking ratio was 100:4,the concentration of gel breaker was 0.02%,the concentration of clay stabilizer KCl was 1.0%,the concentration of bactericide hexamethylenetetramine was 1.50%,the optimum crosslinking pH was 8,and the boron complexing agent was determined by mixing viscosity of backflow fluid and guanidine gum as index.The types and dosages of mannitol and glycerol are 0.75%and 0.65%respectively.The viscosity of mixed solution is equal to that of 0.3%hydroxypropyl guanidine gum,which meets the requirements of fracturing fluid base fluid.By reassigning the viscosity of clean fracturing fluid as an index,1.5%cetyltrimethylammonium chloride and 0.2%YC-1 are added to the clean fracturing fluid backflow,and the temperature resistance limit of reassigned fracturing fluid is 70 C,when gel breaks.The dosage of kerosene is 5%.The mixing ratio of clean fracturing reflux fluid and guanidine gum fracturing fluid is 1:1,the concentration of borax crosslinking agent is 0.5%,and the crosslinking ratio is 100:5. |
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